Radiopharmaceuticals and cancer
Radiopharmaceuticals are specialized therapeutic drugs that contain radioactive isotopes in trace amounts, designed to target and destroy malignant cells in specific areas of the body. They are particularly effective in treating various cancers that have metastasized to bone tissues, including prostate cancer and thyroid cancer, as well as adrenal gland tumors and neuroendocrine tumors. Radiopharmaceuticals can be administered through different routes, such as intravenously, orally, or via direct injection, with the intent to minimize damage to normal cells by delivering radiation directly to the tumor site.
Initially developed for diagnostic purposes, radiopharmaceuticals have evolved since the 1980s to play a significant role in palliative and therapeutic care, especially for patients with cancer that has not responded to chemotherapy. These drugs work by emitting beta particles and gamma rays, which interfere with the cell division process of cancer cells. Advances in the field have led to improved targeting mechanisms, allowing for more precise delivery of treatment to affected areas while sparing healthy tissue.
While radiopharmaceuticals offer valuable benefits, they are not without side effects, which can include a decrease in white blood cell and platelet counts, gastrointestinal issues, and other physical symptoms. Certain populations, like children and older adults, may be more susceptible to these effects. Overall, radiopharmaceuticals represent a critical option in the management of cancer, enhancing quality of life for patients undergoing treatment.
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Radiopharmaceuticals and cancer
ATC CODE: V10
DEFINITION: Radiopharmaceuticals are a class of therapeutic drugs that carry a radioactive isotope in trace quantities. These drugs deliver radiation to kill a targeted region of malignant cells.
Cancers treated: Various cancers metastasizing to bone tissues, especially prostate cancer and thyroid cancer, adrenal gland tumors, neuroendocrine tumors, B-cell non-Hodgkin lymphoma, and polycythemia vera
Subclasses of this group: Radioisotopes of iodine, phosphorous, rhenium, samarium, strontium, and yttrium
Delivery routes: These drugs are administered intravenously, orally in capsule or liquid form, or through a direct injection to the site of cancer on an inpatient or outpatient basis, depending on the specific drug, the type of cancer, and its location. When possible, these drugs are best delivered directly to the tumor site to limit damage to normal cells.
How these drugs work: Initially, radiopharmaceuticals were developed to diagnose various medical problems, including tumors. Using radiographic imaging, nuclear medicine specialists detect the radiation emitted by these drugs and track their activity within an organ. Since the 1980s, the role of radiopharmaceuticals has been expanded to palliation and therapy of metastatic cancers. In this case, a slightly larger amount of the radioactive isotope is used to destroy a group of cancerous cells by interfering with cell division. Instead of photons (used for imaging), the drugs emit beta particles and gamma rays that damage the machinery needed for mitosis. The radioactive isotope is attached to a carrier molecule capable of targeting a specific organ or group of cells. For example, radiopharmaceuticals for bone cancer therapy have a mineral-like carrier molecule taken up by bone tissues.
Radiopharmaceuticals for specific organs may have a monoclonal that recognizes the cell surface receptors of certain tissue cells. Once the drug reaches its target area, the isotope emits radiation slowly over short distances. The half-life, or time required for half of the radiation to be emitted, for these drugs, is two to fifty days, depending on the isotope.
In almost all cases, radiopharmaceuticals are used when chemotherapy has failed or in conjunction with second-line chemotherapy. Radiopharmaceuticals are especially helpful in cancers that have metastasized to neighboring bones, such as prostate and thyroid cancers. Studies have shown that these drugs are valuable in palliative care for patients experiencing pain from cancerous bone tissue, resulting in better disease management and improved quality of life. In the twenty-first century, advances in radiopharmaceuticals increased their effectiveness and accuracy in targeting cancer cells. Radiolabeled conjugates allowed for delivering cancer-fighting medicine directly to cancer cells, sparing healthy surrounding tissues. Theragnostic radionuclides were developed for imaging techniques, allowing for more accurate cancer placement determination and cancer-targeting medicine delivery. Finally, novel carrier systems were developed that delivered radiopharmaceuticals to the precise location needed for treatment.
Side effects: The side effects of radiopharmaceuticals vary depending on the specific radioactive isotope, its dosage, and the individual patient’s physical condition. An excessive dose of these drugs may result in toxicity that affects normal cells as well as malignant cells, which could lead to an intensification of the cancer. The most common side effect of radiopharmaceuticals, however, is a decrease in the patient’s white blood cell and platelet counts. Other common side effects include black or bloody stools, coughs, fevers or chills, back or side pain, difficulty in urination, unusual bleeding or bruising, and nausea and vomiting. Less common side effects include bone pain and irregular heartbeat. Patients who take iodine 131 for thyroid cancer may also experience loss of taste and tenderness in the salivary glands and neck. Since children and older adults are particularly sensitive to radiation, they may experience more side effects during and after treatment with radiopharmaceuticals.
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